Problem with customized login pages for Oracle SSO

[advisories@xxxxxxxxxxxxxxxxxx]

Name:           Problem with customized login pages for Oracle SSO
Id:             MG-2004-01
Issued:         2004-03-30
Authors:        Guido van Rooij (Madison Gurkha)
                Arjan de Vet (Madison Gurkha)
Application:    All known versions
Platforms:      All supported platforms
Reference:      http://www.madison-gurkha.com/advisories/MG-2004-01.txt
CVE:            ---


Description:

        Oracle has a Single Sign-on application called OSSO.

        Among others, it has a web based login form. This form can be
        customized as explained in "Oracle 9iAS Single Sign-on
        Administrators Guide, Release 2(9.0.2), Part No. A96115-01".  In
        this document, a sample login form is published (section 8).

        The problem with this login form is that it can be abused by
        unauthorized persons to gain access to the supplied usercode and
        password. This can be done by tricking a valid user to open a
        URL that is the real URL of the customized SSO login page but
        with a modified URL parameter.

        The problem is that the attack makes use of the real login page.
        Thus, if users check host certificates only, they will not be
        able to detect that they are being tricked. Also, after logging
        in, they can be redirected to the proper application on the
        intended system to hide the fact that usercode and password have
        been stolen.

        Note that the problem is a design problem in the way custom
        login pages must be implemented, not a problem with a sample
        script.

Impact:

        Users can accidentally reveal their SSO usercode/password
        combination to unauthorized persons.

Vendor response:

        Oracle came with the following solution:

          The p_submit_url value in the customized login page can be
          hard-coded.  This will mitigate this issue since it will not be
          an input value to the page anymore. The p_submit_url URL value
          in the 902 SSO server is in the following format:

          http(s)://sso_host:port/pls/orasso/orasso.wwsso_app_admin.ls_login

Recommendation:

        We recommend implementing the proposed solution.

        Of course, we hope that Oracle will update its documentation as
        well such that the p_submit_url parameter will be removed from
        all example code.

History:

        2003-12: discovered
        2004-01-12: vendor informed
        2004-02-18: vendor came with solution
        2004-03-10: communicated solution
        2004-03-30: publication